The present invention relates to a main helicopter rotor. In particular, the present invention relates to an articulated rotor of the type comprising a rotary tubular drive shaft; a hub connected to the top end of the said tubular shaft; a number of blades extending radially outwards from the said hub and each having a pitch change lever; a fixed shaft coaxial with the said rotary shaft and extending at least partially inside the same; an oscillating plate assembly supported on the said fixed shaft; a number of pitch change control rods extending inside the said rotary tubular shaft and connected to the said oscillating plate assembly; a top bell connected to the said hub, for protecting the said oscillating plate assembly; and rocker arms extending through the said bell and each connecting a respective pitch change lever to the said oscillating plate assembly.
On known rotors of the aforementioned type, the tubular shaft usually presents a top flange contacting the bottom surface of the hub, while the top bell presents a bottom flange contacting the top surface of the hub. The said two flanges are connected to each other, through the hub, by means of through pins which, for withstanding local bending stress caused by interacting forces between the tubular shaft and the hub, are driven inside respective through holes formed through the hub itself.
Such a mode of connecting the bell, hub and tubular shaft makes any assembly, dismantling, inspection and/or maintenance work on the oscillating plate assembly extremely difficult, in that access to the said assembly is only possible by dismantling the bell, which is further complicated by having to remove the pins driven through the hub, and the hub off the said tubular shaft.
In other words, therefore, on known rotors of the aforementioned type, any work on the oscillating plate entails dismantling the entire rotor.